You'll see in another post I'm trying to mod a BIOS for something specific - however, this isn't intended to be a double post.

My question here is specifically - can anyone point to resources to learn, at a fundamental level, how Ami BIOSes are laid out, and exactly what each part does please?

My Google-foo fails me - I can find the massive UEFI spec here https://uefi.org/specifications - or I can find hundreds of specific tutorials for specific BIOSes, that are really just a recipe without any understanding.

I'd like to find something in between.